If you're a T-Mobile US customer, or a European smartphone lover, it's not easy choosing between the HTC HD2 and the Nexus One. Yes, they run on different operating systems, but in most other respects, they're quite similar high specs phones with 1GHz Qualcomm Snapdragon CPUs, 5 megapixel autofocus cameras, 3G HSDPA 7.2 Mbps and the usual trio of Bluetooth, WiFi and GPS. The HD2 is a bit cheaper in the US without a contract ($449 vs. $529 for the Nexus One) but the Nexus One is $20 cheaper with a T-Mobile contract (not that $20 is enough money to sway most folks' decisions).

I've owned a Nexus One since early January 2010 when it was first available. I've also been lucky enough to own the Euro version of the HTC HD2 since Nov. 2009. I'm not a stranger to either, and the Nexus One has been my daily driver since it arrived. The HD2 might have been were it not for the lack of 3G on my import model. Now that T-Mobile US has a 3G version, the decision is indeed very difficult.

What sets the HTC HD2 apart is the 4.3" capacitive multi-touch display-- currently the largest capacitive display that can be mass manufactured. It makes for a truly amazing experience when watching videos and viewing photos, web pages, eBooks and Office documents. The Nexus One's 3.7" display suddenly looks kinda small. The Nexus One has more saturated colors thanks to the AMOLED display technology but the human eye perceives sharpness much better than color, so the HD2's display actually looks clearer and sharper. While both phones are large, that huge display means that the HD2 is even bigger than the Nexus One in width and height. Thickness is about the same. If you have small hands, non-limber fingers and are into one-handed operation, the HD2 is probably too wide (in fact, the Nexus One might be as well).

Above: CNN.com on the HTC HD2.Below: CNN.com on the Nexus One

Smackpoint: HTC HD2 wins

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Operating systems... hmmm, that's the big hurt. Android is all new and shiny. It's easy to customize and there are tens of thousands of apps available in the Android Market. Windows Mobile gets bashed on these days-- it's a fashionable target in an industry where being snarky and jaded is the norm. And honestly, there's no way you could get me to use a bone stock, vanilla Windows Mobile device anymore. I loved it 5 years ago but now it's just too old fashioned and un-finger-friendly. But, big but here, HTC's Sense UI (the latest evolution of TouchFLO 3D) has nearly completely replaced the Windows Mobile UI. And it's fast, fun, useful and efficient. If you've used a 2 generations old TouchFLO 3D Windows Mobile phone, this is much, much faster and even more useful. Crazy beatiful weather, a home screen that tells you what you need to know (appointments, calls, shorcuts to apps, weather and time), Twitter, music player, stocks-- lots of good stuff here. You can select which tabs and types of data you want shown and you can add the app shortcuts of your choice, but you can't go beyond HTC's selection of tabs to add something new.

As many of you know, there aren't as many Windows Mobile apps. If you're a software junky that's a major bummer. Windows Mobile Marketplace has less than a thousand apps from my casual count. But WinMo was around long before the on-device marketplace became the norm, and there are many great apps that aren't on the Marketplace. If you're an experienced Windows Mobile user, you probably have your favorites lined up and know where to get more. But for novices, Android is much, much easier. Having used Windows Mobile for years, I have apps for all my needs. And there's crossover for popular apps like Netflix, Weatherbug and Facebook-- get it on the Android Market or get it on the Windows Mobile Marketplace. But I've also come to realize that I need a set of core apps and beyond that, I have about 20 apps I downloaded but rarely use on my iPhone and Nexus One.

What about that non-existent upgrade to Windows Phone 7? I don't think this is a deal breaker. WP7, from what's been shown so far, is a very different animal that seems in many ways more like iPhone OS. It looks like more of a closed ecosystem and those who like WinMo appreciate that it has a file manager, microSD card slot support and it's easy to get your files (all sorts) onto the device.

One advantage WinMo has over Android is the built-in MS Office Mobile suite that can read, write and edit Office files, superb MS Exchange support (no kidding, MS makes both products) and very fast and robust networking. Yet Android wins because of all those apps and because Windows Mobile 6.5, at some point a year or two from now, will be a dead end (MS will continue to offer 6.x and 7 phones for some time, so WM6.x won't disappear come the end of 2010 when Windows Phone 7 is due to debut).

Smackpoint: Nexus One

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Speed: they're both fast with plenty of CPU power and RAM. Both bog down occasionally, but if you vet your 3rd party software, each is stable and doesn't slog down too often.

Smackpoint: tie.

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Android isn't known for its killer multimedia capabilities, but Android OS 2.1 addresses that somewhat. The HD2 ships with the Transformers movie in 800 x 480 resolution, MPEG4 format with high quality stereo audio. The file is 1.5 gigs. We put that movie on the Nexus One and played it with Gallery, the built-in media player. It handled the movie as well as the HD2. But the Nexus One has a pitiful speaker while the HD2 rocked us with sound. The larger HD2 screen meant small details weren't too tiny to notice; a definite score. Both phones did well using headphones, though the HD2 was a bit louder and fuller.

HTC's music player and video player on the HD2 are quite good and help keep you away from the antiquated Windows Media Player Mobile. They're definitely slicker than the stock Android media apps. The HD2 is the first phone to come with Blockbuster's mobile application for buying and renting movies. Very nice for those who travel and need entertainment on the road. But Blockbuster uses DRM and so it's handled by Windows Media Player Mobile. A bland interface but the movies look fine.

Smackpoint: HD2

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Tethering is a popular feature for the road warrior. That means using your phone as a high speed wireless modem over Bluetooth, USB or WiFi. Android and the Nexus don't do tethering unless you want to root your phone. The HD2 has Internet Connection Sharing over USB and Bluetooth. The Euro version has sharing over WiFi too (it works like a Verizon MiFi or the same feature on the Palm Pre), but not the T-Mobile US version. But install MortScript and 1 app from XDA-Developers and you've got 3G connection sharing over WiFi. I've tested it using a notebook and our review HD2 and it works very well.

Smackpoint: HTC HD2 wins.

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Call quality is important, as is reception, even for these devices that are more pocket computers than phones. The Nexus One's Achilles heel is recpetion. It ain't great and if you hold the phone to your head with your hand covering the lower half of the phone it drops a few bars of reception. Mine drops 3G for EDGE every time I hold the phone to my head. The HD2 hasn't done this so far. Using Field Trial on the HTC HD2 and the Status applet on the Nexus One, the HD2 gets about -8db stronger signal than the Nexus on 3G HSDPA, and that's a significant improvement. That said, the HD2 still isn't an RF demon like the Nokia N900 that could almost get a signal in a lead-lined box .

Build quality and looks should be tops on expensive phones, and both the HTC HD2 and Nexus One are solid, well made phones with rigid plastics and metal. Though both are large phones, the curvy and slightly smaller Nexus One is easier to hold in the hand and operate one-handed.

Smackpoint: Nexus One.

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Both phone's cameras look similar on paper. They're both 5 megapixel autofocus and both phones are made by HTC. The HD2 had a dual LED flash that's bright enough to blind a mugger in a dark allway while the Nexus One has a wimpy single LED flash. The Nexus One's photos aren't verry good in terms of sharpness, exposure and color accuracy. The HD2 feels like next generation hardware with a touch focus option (touch the area you want to be the center of focus), fast shot times, VGA video recording and it yieds much sharper images with natural colors and good exposure. The T-Mobile HD2 takes better photos than the import HD2 (HTC has had 5 months to improve things after all).

Smackpoint: HTC HD2

Based on these criteria, the HTC HD2 smacks down the Nexus One. Looking at the big picture, a brand new OS and lots of apps does carry lots of weight, even though it comprises just one comparison point. And in reality, it is a hard choice. Either way you get a great phone and pocket computer.